Append text to an attribute rather than replacing it?

I know this question is 7 years old. Just in case someone came across this question, here's the solution without using .each:

$('.theclass').attr("title", function() { return $(this).attr("title") + "Appended text." });

In that context, $(this) is not the element of $('.theclass'). Maybe you want to use each:

$('.theclass').each(function() {
    $(this).attr("title", $(this).attr("title") + "Appended text.");
});